Yesterday, I decided to run a piece of surveyors tape up the main halyard to act as a telltale. I was sailing to windward for about a mile, and it took about 10 tacks to get there. I was surprised at how often the telltale streamed in line with the mainsail. The wind was south and it puffed and stopped, puffed and stopped constantly. Sometimes the telltale just dangled behind the sail.
I failed to make one tack and ended up in irons. The telltale was hanging in line with the luffing sails. I managed to get out with the help of an oar.
On another tack, I felt the wind dying out and decided to jibe. The telltale wrapped around the mast and stayed there. I couldn't get it to come from around the mast, even after a few tacks. It bothered me.
I came home wing and wing, and somehow the telltale straightened itself out.
Anyhow, I googled telltales and got more info than I ever thought possible. But none of the examples showed telltales at the top of the mast. They were all on the sails in various places.
So, What do you say? Is it wrong to run a telltale from the halyard? Would it be better if it were on top of the mast? What about putting one on each mast? Why would you?